1. Field of the Invention
The present invention relates to an ultrasonic probe used in an ultrasonic treatment device such as an ultrasonic suction device.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2005-27809 has disclosed an ultrasonic treatment device configured to conduct a treatment known as ultrasonic suction and a treatment known as ultrasonic coagulation-and-cutting. This ultrasonic treatment device includes an ultrasonic probe which is configured to transmit ultrasonic vibrations from a proximal end to a distal end. The ultrasonic suction is performed by using a distal face of the ultrasonically vibrating ultrasonic probe, and is performed by using a physical phenomenon known as cavitation. More specifically, as the ultrasonic probe repeats tens of thousands of high-velocity vibrations per second by ultrasonic vibrations, pressure periodically varies in a vicinity of the distal face of the ultrasonic probe. When the pressure in the vicinity of the distal face is lower than saturated vapor pressure for only a short time because of a pressure variation, small air bubbles (cavities) are generated in a liquid within a body cavity or in a liquid supplied from the ultrasonic treatment device to a vicinity of a treatment position of the living tissue. The generated air bubbles disappear because of the force that acts when the pressure in the vicinity of the distal face increases (compression). The above-described physical phenomenon is called a cavitation phenomenon. An inelastic living tissue such as a hepatic cell is shattered and emulsified by impact energy when the air bubbles disappear. A suction path passes through an inside of the ultrasonic probe from the proximal end to the distal end. The shattered and emulsified living tissue is suctioned and collected from a suction opening at the distal end of the ultrasonic probe through the suction path. The above-described functions are continued to resect the living tissue. In this case, an elastic living tissue such as a blood vessel absorbs the impact and is therefore not easily shattered, and the living tissue is selectively shattered. However, while the living tissue is selectively shattered by the cavitation, elastic living tissue such as a blood vessel may also be damaged when the treatment by the cavitation is carried on with the distal end of the ultrasonic probe remaining at the treatment position (affected part) of the living tissue. Therefore, the treatment by the cavitation is conducted with the ultrasonic probe moving along a surface of the treatment position (affected part). As the suction path passes through the ultrasonic probe from the proximal end to the distal end, the ultrasonic probe has a cylindrical shape.